Coating method and device

Abstract

The present invention provides a method and apparatus for coating a strip-shaped flexible dielectric substrate with a metal layer on a coating roller, wherein during the coating, the substrate is guided onto the coating roller along the longitudinal direction of the substrate. The substrate is charged to improve the adhesion of the substrate to the coating roller during the coating. A first metal layer is coated on the substrate, wherein at least one blank strip is retained along the longitudinal direction of the substrate, and a second metal layer is provided on the coated substrate.

Description

[0001] The present invention relates to a method and a device for coating a strip-shaped flexible dielectric substrate, in particular to a method and a device for coating such a substrate multiple times.

[0002] For coating of strip-shaped substrates, such as films, on coating rollers, it is known to provide the substrate with an electrical charge before coating in order to increase the adhesion of the substrate to the coating roller. The substrate is charged, for example, by means of an electron beam, which is directed at the substrate before the substrate comes into contact with the coating roller. The electrical charge causes the substrate to adhere firmly to the roller, thereby significantly improving the cooling of the substrate during the coating process. It is thus possible to increase the coating rate and / or reduce the thickness of the substrate. Such a method is known, for example, under the name SuperBias.

[0003] EP 1 686 197 B1 describes a vacuum evaporation deposition method and apparatus, in which a layer of insulating material to be applied is brought into close contact with a cooling roller by means of electrical charging.

[0004] Charging a substrate requires a dielectric substrate; a conductive substrate cannot be charged by an electron beam. Substrates that have been provided with a metal coating in a previous step cannot be charged by an electron beam. Such a coating also renders the originally dielectric substrate conductive, which makes subsequent charging no longer possible or reduces the effectiveness of previously performed charging.

[0005] For this reason, the advantages of the known method can only be realized in the case of a one-time coating, ie only a single-sided coating.

[0006] The object of the present invention is therefore to achieve the advantageous effect of charging also for substrates which have already been metallized in a preceding process step. In particular, an improvement of the coating process should be achieved so that it can also be used for processes for multiple coating of substrates, wherein at least one of the coating processes comprises a metallization, such as multiple coating or double-sided coating. Thus, an improvement of the coating process after the metallization should also be achieved.

[0007] These objects are achieved by the features of the invention according to the independent claims; the dependent claims define embodiments of the invention.

[0008] The basic idea of ​​the invention is that when metallizing a substrate, the substrate is not coated over the entire width, but at least one longitudinal strip of the substrate is provided along which no coating is performed. These strips of the substrate which are not provided with a metal layer can then retain the effect of the previously performed charging or can be charged anew, so that at least along the strips which remain free, the increased adhesion of the substrate to the coating roller is retained. The subsequent further coating can then be performed on the same surface or on the back side, preferably again in the part of the substrate which was coated during the first coating.

[0009] In particular, the present invention provides a method for coating a strip-shaped flexible dielectric substrate with a metal layer on a coating roller, wherein during the coating, the substrate is guided onto the coating roller in the longitudinal direction of the substrate. The substrate is charged to improve the adhesion of the substrate to the coating roller during the coating. The substrate is coated with a first metal layer, wherein at least one blank strip is retained along the longitudinal direction of the substrate, and a second metal layer is provided for the coated substrate. The at least one blank strip is preferably provided around at least one longitudinal edge of the substrate, wherein preferably at least two blank strips are retained, wherein the two longitudinal edges of the substrate are each surrounded by one of the blank strips, and the blank strips are spaced a certain distance in the width direction, and the distance is preferably constant in the longitudinal direction of the substrate.

[0010] Prior to step (b), step (a1) for treating the portion of the surface to be coated of the substrate where the blank strips should remain can be performed in such a way that the metal layer is not applied in these blank strips. The treatment can have at least one of the following: applying oil or other media using an evaporation method or an offset printing method, which evaporates after a certain time in a vacuum; covering with the aid of a shielding device; causing an air flow to blow away the metal vapor; absorbing the metal vapor; applying a protective medium; evaporating the metal coating in situ; and creating an area with a sharp decrease in conductivity.

[0011] In step (b), one surface of the substrate may be coated, wherein in step (c), the same surface of the substrate is coated with another layer. Likewise, in step (b), one surface of the substrate may be coated, and in step (c), the opposite surface of the substrate may be coated, the opposite surface being the surface coated in step (b).

[0012] Prior to step (c), the portion of the substrate opposite the surface to be coated in step (c) where the blank stripe is to remain may be treated to ensure that the blank stripe remains blank,

[0013] Preferably, the blank strip on the opposite surface corresponds to the retained portion of the surface in step (b).

[0014] Alternatively, the first layer and, if necessary, the subsequent layers may be applied alternately to the one surface of the substrate and the opposite surface of the substrate, which is the opposite side of the surface coated in step (b).

[0015] The method may also include coating the substrate with further metal layers.

[0016] If necessary, a step of recharging the substrate may be performed before at least one of the steps of coating the substrate with a second metal layer or more metal layers.

[0017] The coating of the substrate is carried out in particular by means of a vacuum vapor deposition method.

[0018] The present invention also provides a device for coating a strip-shaped flexible dielectric substrate with a metal layer on a coating roller, wherein during the coating, the substrate is guided onto the coating roller along the longitudinal direction of the substrate. The device has:

[0019] a device for charging the substrate to improve adhesion of the substrate to the coating roller during coating;

[0020] means for coating a substrate with a first metal layer,

[0021] wherein the device is configured such that during coating, at least one blank strip remains along the longitudinal direction of the substrate, to which the metal layer is not applied; and

[0022] A device for applying a second metal layer to a coated substrate.

[0023] The apparatus may also have means for applying a second metal layer to an opposing surface of the substrate.

[0024] Furthermore, the device for treating those parts of the surface to be coated of the substrate in which the free strips are to remain can be arranged in such a way that application of the metal layer in these free strips is avoided.

[0025] The invention makes it possible to achieve the advantages of charging the substrate even during the coating process of a substrate which is already provided with a metallic coating.

[0026] The present invention will be explained in more detail below with reference to the accompanying drawings;

[0027] Figure 1 Schematically shows a top view and a side view of a strip-shaped substrate provided with a metal layer by the method according to the invention, and

[0028] Figure 2 A coating roller is shown for illustrating a second coating process according to an embodiment of the present invention.

[0029] During coating, in particular during vacuum coating processes for coating film webs in the production of electronic components, for example during the coating of aluminum (Al) layers in battery production or also in the packaging industry, the film to be coated (substrate) is guided onto rollers and the actual coating is carried out while the film runs over the coating rollers. For example, the coating can be applied to the substrate by a vapor deposition method or a sputtering method.

[0030] Thus, in particular in the production of packaging films, as well as in the production of capacitors or electrodes in battery production, increasingly thicker metal layers, in particular aluminum layers, are required on relatively thick substrates. Correspondingly, even with these thicker layers, the coating time should not be significantly increased. Thus, for example, with previous methods it was only possible to achieve coating rates of up to about 10 m / s on a web substrate with a layer thickness of 50 nm Al. However, now in battery production, for example in the production of current collectors, layer thicknesses of 500 nm or even 1.5 μm Al are already required on films with a thickness of only 8 μm. This was difficult to achieve with previous vacuum coating methods. Due to the high coating rates, the heat of condensation on the substrate increases, thereby increasing the heat input transferred to the substrate, which has to be dissipated during coating. Therefore, what is needed is a method that can increase the cooling capacity of the coating roller.

[0031] By charging the substrate before coating, for example by means of an electron beam on the side facing away from the roller, the adhesion of the substrate to the coating roller is improved by electromagnetic forces. As a result, the condensation heat generated during coating can be dissipated better via the roller.

[0032] This can be successful in dielectric substrates used for the first coating process. However, in particular in the above-mentioned application areas, it is often necessary to apply two or more metal layers to the substrate and / or to provide two surfaces of the substrate with metal layers. An example for this is the production of cathode pairs / anode pairs. However, if the metal layer is applied to the substrate, the substrate loses its dielectric properties and it is no longer possible to apply an electric charge to the substrate.

[0033] In order to make it possible for the already metallized substrate to adhere to the coating roller even in the subsequent coating process by means of the charging device already used in the first coating process, according to the invention, at least one free stripe is left in the longitudinal direction of the substrate during the metallization process. That is, the metal coating is not applied over the entire width of the substrate, but rather along at least one stripe, preferably at least two or more stripes, so that an area remains on the substrate to which a previously applied charge can be applied and / or to which a charge can be applied in the subsequent charging process. As a result, adhesion to the coating roller can be increased at least in the free stripe and heat transfer to the roller can be ensured.

[0034] Figure 1The corresponding coated substrate 1 is schematically shown in a top view and a side view. Along the longitudinal direction L of the substrate 1 to be coated, which can be provided in strips of up to several thousand meters in length, the strips 12 are provided with the coating, while the strips 11 located therebetween remain free (free strips 11). The free strips 11 or areas must, on the one hand, be wide enough to ensure sufficient adhesion of the partially metallized substrate 1; on the other hand, the width of the strips 11 should be chosen to be as narrow as possible, since the free areas can no longer be used to produce the desired product later.

[0035] In order to avoid coating the substrate in the desired areas, the corresponding areas can be treated before coating. For example, a layer of oil can be applied before coating in the areas of the strip 11 that are not to be coated. This can preferably be performed by an offset printing method. It is also possible to use an oil evaporation method, for example in the form of a strip oil evaporator. Generally, the use of oil is preferred because oil (or other suitable hydrocarbons) evaporate after a certain time in a vacuum without damaging the substrate. Such substances evaporate during the subsequent vacuum coating and / or evaporate during the coating due to heating of the boundary layer.

[0036] At the locations where the oil layer was applied, the substrate cannot be permanently metallized and the previously applied charge remains in these areas. During the subsequent coating process, these areas still cause the substrate to adhere to the coating roller despite the metal coating in the remaining areas.

[0037] Other possibilities for locally preventing metal coating on the substrate 1 are, for example, covering the corresponding areas with the aid of a shielding device or applying a protective medium or purposefully causing a gas flow to blow away or absorb metal vapor. Furthermore, the applied metal layer can also be purposefully evaporated in situ in the corresponding areas of the strips 11 to be left blank, for example by the action of a local heat source, such as an infrared laser. It is also possible to create areas with a sharp decrease in conductivity in the corresponding strips 11 before coating by reactively dielectrically coating the metal in the area of ​​the blank strips 11.

[0038] The method according to the invention can also be carried out several times in succession, wherein after each local treatment to prevent coating and subsequent coating, the substrate is again provided with local areas, preferably in the same areas as in the first process, in which local areas coating is to be prevented, and the substrate is subsequently coated again. Thus, not only the coating itself can be carried out several times in succession, but also intermediate treatment steps of areas not to be provided with coating, for example oiling by means of a strip oil evaporator.

[0039] In addition, the coating device for coating the front and back sides of the substrate in one working step may also have further devices for applying the metal layer, namely in particular a second coating roller and, if necessary, a second device for treating the substrate on the back side to prevent coating in areas that are to remain clear.

[0040] For example, in a substrate with a width of about 20 cm, four strips of about 3 to 4 cm each can be applied, each of which is separated by a blank strip of about 1 cm. Likewise, substrates with a width of, for example, 600 mm to 700 mm and a length of 1.3 m to 1.7 m can also be used. This can be used, for example, for the production of batteries, which should have a certain size, for example approximately equal to the DIN A4 or A5 size, wherein the width of the strips can then be adjusted accordingly.

[0041] Preferably, a blank strip 11 is left at both edges along the longitudinal direction of the substrate 1. Preferably, the strip pattern is formed symmetrically on the substrate. The substrate can also be treated from both sides in such a way that the same areas remain free of coating on the front and back. This is particularly preferred for the case where a metal coating is to be applied on both sides of the substrate 1. This creates areas that always remain free of metal coating despite turning the substrate 1 over for double-sided coating or multiple coating on both sides. Despite the turning over, these areas repeatedly improve adhesion and always contain air cushions, which maintain optimal cooling, as will be described below. Figure 2 This is explained in more detail.

[0042] Figure 2 A coating roller 20 is schematically shown, onto which a substrate 1 which has been coated with a metal layer in a first coating process according to the method of the invention is guided. In the strip-shaped regions coated with the metal layer, the charge which has been applied before the first coating or which has been newly applied after the first coating no longer provides an effect of adhering the substrate 1 at the coating roller 20. Instead, an air cushion 31 is formed in these regions between the roller 20 and the substrate 1. As described above, the air cushion 31 thus formed supports the cooling of the substrate 1. In these regions, a gaseous medium can be introduced by suitable means to strengthen the effect of the air cushion.

[0043] The remaining areas 11' of the substrate 1 are already coated with an oil film 32, which prevents the substrate from being coated in these areas 11'. At these locations, the substrate 1 is attached to the roller 20, so that an air cushion 31 is formed in the middle area to ensure cooling and ensure optimal coating of the metal vapor 4 arranged around the roller.

[0044] Therefore, in addition to the method, the invention also provides a corresponding device for coating a substrate, which has a device for charging the substrate, in particular by means of an electron beam; a device for treating the substrate to ensure that the desired blank strips are not coated, for example a device for local coating with a thin oil film; and finally a device for coating the substrate on the surface, in particular a device for coating with a coating roller, for example a vacuum evaporation device. The coating device, and optionally the charging and / or treatment device, can then use the advantages of the incomplete metal coating again after the first coating for a second coating on the same side or also on the opposite side and, if necessary, further coatings, or, as described above, can each be provided with a second device in order to apply the first and second coatings in one process step, in particular on the front and back sides of the substrate.

[0045] Although the present invention is illustrated and described in detail with the aid of the accompanying drawings and the related description, the illustration and the detailed description should be understood as illustrative and exemplary, rather than limiting the present invention. It should be understood that those skilled in the art may make changes and modifications without departing from the scope of the following claims. In particular, the present invention also includes embodiments having any combination of the features mentioned or illustrated above for different aspects and / or embodiments.

[0046] The invention also includes individual features in the figures, even if these are shown in combination with other features in the figures and / or have not been mentioned above.

[0047] Furthermore, the terms "having", "including" and their derivatives do not exclude other elements or steps. Likewise, the indefinite article "a" or "an" and their derivatives do not exclude a plurality. The functions of multiple features listed in the claims can be realized by one unit. In particular, the terms "substantially", "approximately", "roughly" and the like in conjunction with a characteristic or value also precisely define the characteristic or precisely define the value. All reference numerals in the claims should not be understood as limiting the scope of the claims.

Claims

1. A method for coating a strip-shaped flexible dielectric substrate (1) with a metal layer on a coating roller (20), during which the substrate (1) is guided onto the coating roller along the longitudinal direction (L) of the substrate (1), the method comprising the following steps: (a) charging the substrate (1) to improve the adhesion of the substrate (1) to the coating roller (20) during the metal coating; (b) coating the substrate (1) with a first metal layer, wherein at least one blank strip (11) is retained along the longitudinal direction (L) of the substrate (1), and the blank strip is not coated with the metal layer; (c) applying a second metal layer to the coated substrate; Wherein, the method further comprises: (d) after coating the substrate (1) with the first metal layer, before carrying out at least one of the step (c) of coating the substrate (1) with the second metal layer and the step of coating the substrate (1) with further metal layers, recharging the substrate (1); and A step of introducing a gaseous medium; wherein, when the coated substrate is coated in step (c), an air cushion (31) is formed between the coating roller (20) and the substrate (1) in the portion of the surface of the substrate coated with the first metal layer in step (b); wherein the step of introducing a gaseous medium comprises: introducing a gaseous medium in the portion to enhance the effect of the air cushion.

2. The method according to claim 1, wherein the at least one blank strip (11) is arranged around at least one longitudinal edge of the substrate (1).

3. A method according to one of the preceding claims, wherein at least two blank strips (11) are retained, wherein the two longitudinal edges of the substrate (1) are each surrounded by one of the blank strips, and the blank strips are spaced a certain distance apart in the width direction, and the distance is preferably kept constant in the longitudinal direction (L) of the substrate (1).

4. The method according to claim 1 or 2, further comprising a step (a1) performed before the step (b) for treating the portion of the surface to be coated of the substrate (1) where the blank strip (11) should be retained, so as to avoid coating the metal layer in the blank strip (11). The treatment preferably comprises at least one of the following: Applying oil or other media using evaporation or offset methods, said media evaporating after a certain time in a vacuum; Covering with the help of a shielding device; Allowing air flow to act to blow away metal vapor; Absorb metal vapor; Apply protective medium; In-situ evaporation of metal coatings; as well as Creates areas where conductivity decreases dramatically.

5. The method according to claim 1 or 2, wherein in the step (b), one surface of the substrate (1) is coated, and in the step (c), another layer is coated on the same surface of the substrate (1).

6. A method according to claim 1 or 2, wherein in step (b), one surface of the substrate (1) is coated, and in step (c), the opposite surface of the substrate (1) is coated, the opposite surface being the reverse side of the surface coated in step (b).

7. The method according to claim 6, wherein before step (c), the portion of the substrate to be coated in step (c) on which the blank strip (11) is to be retained is treated to ensure that the blank strip (11) remains blank, Preferably, the blank strip (11) of the opposite surface corresponds to the retained portion of the surface in step (b).

8. A method according to claim 6, wherein a first layer and, if necessary, subsequent layers are applied alternately to said one surface of the substrate (1) and to said opposite surface of the substrate (1), said opposite surface being the reverse side of said surface coated in said step (b).

9. The method according to claim 1 or 2, wherein the method further comprises coating the substrate (1) with further metal layers.

10. The method according to claim 1 or 2, wherein the coating of the substrate (1) is carried out by means of a vacuum evaporation method.

11. A device for coating a strip-shaped flexible dielectric substrate (1) with a metal layer on a coating roller (20), during which the substrate (1) is guided onto the coating roller along the longitudinal direction (L) of the substrate (1), wherein the device has: (a) a device for charging the substrate (1) to improve the adhesion of the substrate (1) to the coating roller (20) during the application of the metal layer; (b) a device for coating the substrate (1) with a first metal layer, wherein the device is configured such that during the coating at least one blank strip (11) remains along the longitudinal direction (L) of the substrate (1), to which the metal layer is not applied; (c) means for applying a second metal layer to the coated substrate; (d) a device for recharging the substrate (1) after coating the substrate (1) with the first metal layer and before carrying out at least one of the steps of coating the substrate (1) with the second metal layer and coating the substrate (1) with further metal layers; and A device for introducing a gaseous medium; wherein, when coating the coated substrate, an air cushion (31) is formed between the coating roller (20) and the substrate (1) in the portion of the surface of the substrate coated with the first metal layer; wherein the device for introducing a gaseous medium is used to introduce a gaseous medium in the portion to enhance the effect of the air cushion.

12. The device according to claim 11, further comprising means for applying a second metal layer on the opposite surface of the substrate (1).

13. The device according to claim 11 or 12, further comprising a device for treating the portion of the surface to be coated of the substrate where the blank strip (11) should be retained, so as to avoid coating the metal layer in the blank strip (11).

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